Bellows sealed stem for rotary valve

ABSTRACT

A valve body includes a chamber for the flow of fluid between an inlet and outlet thereto. A valve member, such as a ball valve member, is positioned in the chamber for rotatable movement between an open position and a closed position to open and close the chamber. A bent valve stem extends between and is connected to the valve member and a rotatable valve actuator. Rotation of the actuator moves the valve member by rotation of the valve stem between the open and closed positions. The valve stem upper end portion is displaced from the valve stem lower end portion to provide the valve stem with a bent configuration. A bellows surrounds the valve stem to provide a hermetic seal around the stem between the valve body and the actuator. The bellows has a bent configuration corresponding to the bent configuration of the valve stem. The other surface of the valve stem is positioned closely adjacent to the inner surface of the bellows to provide the bellows with support substantially along the entire length of the bellows and means are provided to minimize wear between the bellows and stem. In operation, the bellows is internally pressurized and the support provided by the valve stem prevents lateral deflection of the bellows and failure of the bellows due to distortion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a valve and more particularly to a rotaryvalve having a bent valve stem enclosed and hermetically sealed by abent bellows which is internally pressurized during operation of thevalve and supported substantially along its entire length by the valvestem to resist lateral deflection and distortion of the bellows andthereby prevent failure of the bellows seal.

2. Description of the Prior Art

In rotary valves, such as butterfly, ball, plug and the like, forconveyance of fluids and particularly contaminated fluids at highpressure, as well as at substantially reduced pressure or under vacuumconditions, it is preferred to utilize static seals as opposed to packedor dynamic seals. Packed or dynamic seals are subject to wear resultingin valve leakage, particularly at the pressure boundary between thevalve stem and the valve member. A commonly used static seal is abellows surrounding the valve stem. U.S. Pat. Nos. 1,644,825; 2,659,569;2,659,570 and 3,811,651 disclose rotary valves that utilize a bellowsfor sealing around the valve stem between the valve actuator and thevalve member.

Conventionally, a bellows, when used to seal a valve stem, is bonded orwelded to the structure of the valve body that supports the rotatablevalve member at one end and at the opposite end to a retainer or capthat connects the valve stem to the valve actuator. This arrangement isillustrated in U.S. Pat. No. 3,811,651. Because the connections at theends of the bellows are metal-to-metal, a static seal is formed. It isknown to laterally deflect the valve stem or utilize a crank-like valvestem and hermetically seal the stem in the bellows. In this manner, thevalve stem connects the actuator to the valve member to preventtorsional loading of the bellows, as illustrated in U.S. Pat. Nos.1,644,825 and 3,811,651.

One of the difficulties encountered with a bent valve stem hermeticallysealed in a bellows of the type described above is that the bellows mustalso bend in order to enclose the valve. Thus, the bellows is initiallyflexed and therefore is subject to lateral distortion or "squirming". Abellows by its flexible nature when subjected to axial compression tendsto deflect laterally or "squirm". This will occur at relatively lowforces.

When a bellows is internally pressurized, the pressure applied to theinside of the bellows around the valve stem tends to outwardly deflectthe bellows. Therefore, a bellows is subject to failure to a muchgreater degree when subjected to internal pressure and laterallydeflected. This problem is magnified when the bellows is initiallyflexed or bent.

While it has been suggested by the prior art devices to use a bellows tohermetically seal a valve stem particularly as a static seal around abent valve stem, a bent bellows is unstable and therefore subject todistortion and consequent bellows failure. Therefore, there is a need innon-rising rotary valves for a bent bellows valve seal which issupported to resist lateral deflection when the bellows is internallypressurized and prevent bellows failure.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a valve thatincludes a valve body and a passageway extending through the valve bodyfor the flow of fluid therethrough. A valve member is positioned in thepassageway for movement between an open position and a closed positionto open and close the passageway. Actuating means rotatable about anaxis moves the valve member between the open and the closed positions. Avalve stem extends between the valve member and the actuating means. Thevalve stem has a lower end portion connected to the valve member and anupper end portion connected to the actuating means for transmission ofrotation of the actuating means to the valve member. The valve stemupper end portion is displaced from the valve stem lower end portion toprovide the valve stem with a bent configuration. A bellows surroundsthe valve stem to provide a hermetic seal around the valve stem betweenthe valve body and the actuating means. The bellows has a bentconfiguration corresponding to the bent configuration of the valve stem.The valve stem has an outer surface and the bellows has an inner surfacepositioned closely adjacent to the valve stem outer surface such thatthe valve stem supports the bellows against lateral deflection whensubjected to pressure forces to prevent distortion of the bellows.

The bellows is initially flexed around the valve stem. A close toleranceis provided between the valve stem and the bellows so that the bellowsis substantially supported along its flexed length by the valve stem.The valve stem thus restrains uncontrolled buckling or "squirm" of thebellows and the bellows can withstand higher pressures. By increasingthe surface contact between the bellows and the valve stem localizeddistortion or buckling of the bellows at concentrated points iseliminated.

In one embodiment, the valve stem includes a low friction outer surfaceor stem coating for preventing wear of the bellows by contact with thevalve stem. In one embodiment suitable bearing means surrounding thevalve stem supports the bellows on the valve stem. The bearing meanspermits relative movement between the bellows and the valve stem buteliminates frictional engagement of the bellows with the valve stem.

In another embodiment, the valve stem is provided with a wear resistantsleeve fabricated of a suitable material for reducing the frictiongenerated by rubbing of the bellows on the valve stem. The sleeve may beunitary or a stacked arrangement of individual rings secured to thevalve stem and dimensioned to contact the inner surface of the bellows.Preferably, the sleeve is fabricated of a material which provides abellows wear resistant surface that can be either softer or harder thanthe bellows material.

Further in accordance with the present invention the inner surface ofthe bellows is reinforced by plating, particularly at the radii of theconvolutions where the wear is the greatest. A selected wear resistantmaterial is bonded or secured to the inner surface of the bellows andprojects inwardly of the radii of the convolutes. Wear of the innersurface of the bellows is also reduced by the provision of flatsextending between the convolutes on the inner surface of the bellows.The flats extend parallel to the surface of the valve stem and thusserve to distribute contact of the bellows with the valve stem over agreater surface area of the bellows. This eliminates localized stresspoints on the bellows and reduces resultant abrasion of the bellows.

Accordingly, the principal object of the present invention is to providea rotary valve having a bent valve stem enclosed by a bent bellows whichis supported substantially along its entire flexed length by the valvestem to resist lateral deflection and distortion of the bellows andthereby prevent failure of the seal provided by the bellows around thevalve stem.

A further object of the present invention is to provide in a rotaryvalve a bent valve stem hermetically sealed by a bent bellows which issupported by the valve stem against buckling when the bellows isinternally pressurized.

Another object of the present invention is to provide a bellows sealedvalve stem for a rotary valve in which abrasive wear of the bellows byfrictional contact with the valve stem is reduced.

A further object of the present invention is to provide a bellowsfailure indicator for a valve having a valve stem hermetically sealed bya bellows where failure of the bellows seal is detected and the fluidand line pressure are contained in the event of bellows failure.

These and other object of the present invention will be more completelydisclosed and described in the following specification, the accompanyingdrawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view in side elevation of a ball valve,illustrating a bent valve stem hermetically sealed by a bellowsrotatably supported by the crankarm of a valve actuator.

FIG. lA is an enlarged fragmentary sectional view of a connection of thevalve stem to the valve member, illustrating a dynamic seal around thevalve stem.

FIG. 2 is a top plan view of the valve actuator, illustrating the crankarm.

FIG. 3 is a fragmentary view in side elevation, taken along the lineIII--III of FIG. 2, illustrating a welded connection of the bellows tothe valve body to form a hermetically sealed pressure boundary aroundthe lower end of the valve stem, the details of the connection of thestem to the actuator being omitted.

FIG. 4 is a view similar to FIG. 3, illustrating another embodiment of astop mechanism for the valve stem.

FIG. 5 is an enlarged fragmentary sectional view of the valve stem andsurrounding bellows, illustrating plating on the inner surface of thebellows to reduce bellows wear.

FIG. 6 is a fragmentary schematic view of the bellows surrounding thevalve stem, illustrating a further embodiment of plating on the innersurface of the bellows.

FIGS. 7-10 are fragmentary schematic illustrations of variousembodiments for reducing frictional wear of the bellows by contact withthe valve stem.

FIG. 11 is a fragmentary schematic illustration of a bellows failureindicator adaptable for use with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings and particularly to FIGS. 1 and 2, there isillustrated a valve assembly generally designated by the numeral 10 ofthe ball type for controlling the flow of fluid, either a liquid or agas, through a piping system. The valve assembly 10 includes a valvebody generally designated by the numeral 12 having a pair of conduitportions 14 and 16 connected by bolts 18 to a central body portion 20.The conduit portions 14 and 16 are received within a cavity 22 of thecentral body portion. Positioned within the cavity 22 and abutting theadjacent ends of the conduit portions 14 and 16 are valve seats 24. Thevalve seats 24 are rigidly positioned in the cavity 22 by the centralbody portion 20 and the conduits 14 and 16, thereby forming a valvechamber generally designated by the numeral 26. Valve chamber 26communicates with passageways 28 and 30 that extend through the conduitportions 14 and 16 respectively. The passageways 28 and 30 are alignedwith the passageway 32 that extends through the valve seats 24. Theconduit portions 14 and 16 are adaptable for connection to serviceconduits by any suitable means, such as threading the service conduitinto the end portions 14 and 16. In this manner, a continuous passagewayis provided through the valve assembly 10.

A rotatably mounted valve member 34 is connected to a valve stem 36 thatis rotated by a valve actuator generally designated by the numeral 38.The valve member 34 illustrated in FIG. 1 is characteristic of the valvemember utilized in ball-type valves but it should be understood inaccordance with the present invention that other suitable rotary-typevalve members may be utilized such as a butterfly, plug and the like.The valve member 34 includes a body portion 40 having an arcuate surface42. The arcuate surface 42 remains in contact with the valve seat 24 asthe body portion 40 is rotated in the valve chamber 26. The body portion40 has a through bore 44 movable into and out of alignment with thepassageways 28 and 30 of conduits 14 and 16 and passageway 32 of valveseats 24 to permit the flow of fluid through the conduit portions 14 and16 and central body portion 20. Rotation of the valve stem 36 through90° moves the valve member 34 between the open and closed positions.

Movement of the valve member 34 between the open position, asillustrated in FIG. 1 and the closed position (not shown) is controlledby orbital movement of the valve actuator 38 about an axis 46 which iscoaxially aligned with a lower end portion 48 of the valve stem 36. Thevalve stem lower end portion 48 is nonrotatably connected to the valvemember 34. The valve stem lower end portion 48 and the valve member 34are rotatable about an axis 50. As seen in FIG. 1, axis 50 is coaxiallyaligned with the actuator axis 46. The valve stem 36 also includes anupper end portion 52 connected to the valve actuator 38. The valve stemupper end portion 52 has an axis 54 which is laterally displaced fromboth axes 46 and 50. Further as illustrated in FIG. 1, the axis 54 isparallel to the axes 46 and 50. With this arrangement, the axis 54 iseccentric to the axes 46 and 50. The valve stem upper end portion 52 isconnected to the actuator 38 so that torque is transmitted from theactuator 38 to the valve stem 36 and the valve member 34.

The valve stem 36 is a unitary member between the end portions 48 and 52and has a preselected curvature which is a double or reversed curvature.The valve stem upper end portion 52 is rotatably connected to theactuator 38 by a bearing assembly generally designated by the numeral56. A bellows 58 surrounds the valve stem 36 between the upper and lowerend portions 48 and 52. The bellows 58 has a generally cylindrical bodyportion 60 unitary in length and comprising a circumferentiallycorrugated, axially extending, relatively thin cylindrical wall.Normally the bellows is not bent and upon installation, bends to followthe shape of the valve stem. Preferably, the bellows 58 is metallic,impermeable, and sufficiently flexible to withstand the bending thatoccurs in operation. The bellows 58 has a passageway 62 extendingbetween a lower open end portion 64 and an upper open end portion 66.Preferably the bellows 58 has an inner diameter positioned closelyadjacent the outer diameter of the valve stem 36. In one example, thebellows inner diameter is removed from the outer diameter of the valvestem by a distance equal to 10% of the valve stem diameter. With thisarrangement, the valve stem 36 contacts and supports the bellows 58 toprevent lateral distortion or "squirming" of the bellows 58 whensubjected to internal and external fluid pressure. The reverse curvatureof the valve stem 36 results in contact of the bellows 58 with the valvestem 36 and curvature of the bellows 58 conforming to the curvature ofthe valve stem 36.

The bellows upper end portion 66 is connected to the actuator 38 topermit relative rotation between the actuator 38 and the bellows upperend portion 66 for transmission of torque from the actuator 38 throughthe bellows 58 to the valve stem 36. The bellows upper end portion 66 isaxially aligned with the valve stem upper end portion 52 and is part ofa primary pressure boundary around the valve stem upper end portion 52.The bellows lower end portion 64 is axially aligned with the valve stemlower end portion 48 on the axis 50.

The bellows upper end portion 66 is connected in a manner to beexplained later in greater detail to the actuator 38 to form a primarypressure boundary around the valve stem upper end portion 42. Thebellows lower end portion 66 is connected by a weld 67 to a bellowsplate 68 to form a primary pressure boundary around the valve stem lowerend portion 48. The bellows plate 68 is suitably sealingly connected tothe valve central body portion 20 to provide a seal around the stemlower end portion 48 at the point where the stem 36 extends from thecentral body portion 20.

The bellows plate 68 includes a bore 69 through which the valve stem 36extends. The bore 69 is aligned with a bore 71 through the valve centralbody portion 20 that receives the valve stem lower end portion 48.Positioned within the central body portion 20 and the bellows plate 68is a suitable journal-type bearing 70 or bushing. The bearing 70rotatably supports the valve stem lower end portion 48 within the valvecentral body portion 20 and the bellows plate 68.

The bellows plate 68 is suitably connected to the valve central bodyportion 20. As illustrated in FIG. 1, the bellows plate 68 is connectedby bolts 72 to the central body portion 20. FIGS. 3 and 4 illustrate analternate embodiment of the connection of the bellows plate 68 to thecentral body portion 20. In FIGS. 3 and 4, the plate 68 is shownconnected by a circumferential weld at 74 on the upper surface of thevalve central body portion 20 around the bellows plate 68. Thisarrangement forms a welded hermetic seal at the valve stem lower endportion 48 for the 90° operation of the valve member 34. A static O-ringseal 76, shown in FIG. 1, is positioned between the bellows plate 68 andthe valve central body portion 20 to provide a seal therebetween andaround the valve stem lower end portion 48.

In a further embodiment illustrated in FIG. lA a dynamic O-ring seal 77is positioned in a recess of the valve central body portion 20 insurrounding and sealing engagement with the valve stem lower end portion48. The O-ring seal 77 has an inverted U-shape which permits it toexpand outwardly into increased sealing engagement with the valve stemlower end portion 48 in the event of fluid leakage between the valveseats 24 and the valve member 34. This one way seal prevents flow offluid upwardly around the valve stem 36, but allows pressure to escapefrom the bellows 58 to the cavity 22. The seal 77 is operable tominimize the pressure in the bellows to provide a safety margin for thebellows cycle life. The seal 77 further promotes bellows cycle life byminimizing the bellows/stem exposure to potentially abrasive ordeleterious fluids in the valve. The one way nature of the seal 77prevents high pressure from being trapped inside the bellows if thepressure in the valve decreases.

As illustrated in FIG. 1, the actuator 38 includes a crank arm 78rotatable about the axis 46. The crank arm 78 is rotatably supportedwithin an actuator housing 80 that is connected by bolts 82 insurrounding relation with the bellows plate 68 to the upper surface ofthe valve central body portion 20. The housing 80 forms a chamber 84surrounding the valve stem 36 and the bellows 58 and serves as asecondary pressure boundary around the valve stem 36 to back-up theprimary pressure boundary formed by the bellows 58 around the stem 36.With this arrangement, in the event of any leakage around the valve stem36 and through the bellows 58, the housing 80 will contain the leakageand line pressure within the chamber 84.

A static seal is provided by an O-ring 86 between the flanged lower endportion of the housing 80 and the upper surface of the valve centralbody portion 20. Further, a dynamic seal is provided around the crankarm 78 by an O-ring 88 retained within a recess of the reduced upper endportion of the housing 80. The O-ring 88 sealingly engages the outersurface of the crank arm 78.

Rotation is transmitted to the crank arm 78 by a handle 90 that isnonrotatably connected to crank arm 78 by a nut and bolt combination 92.Thus, turning the handle 90 through a preselected degree of rotationrotates the crank arm 78 about the rotational axis 46 to orbit the valvestem upper end portion 52 about the axis 46 and thereby rotate the valvestem lower end portion 48 about the axis 50 to, in turn, rotate thevalve member 34 between the open and closed positions. The crank arm 78includes an enlarged lower end portion 94 offset from the axis 46. Theend portion 94 is rotatably supported within the housing 80 by abushing-type thrust bearing 96 operable to carry axial and radial thrustloads and rotatably support the crank arm enlarged end portion 94. Thethrust bearing 96 is also operable to resist axial movement of theenlarged lower end portion 94 as the pressure increases within thebellows 58. The enlarged end portion 94 includes a recess 98 in whichthe axis of the recess 98 is aligned with the axis 54 of the stem upperend portion 52. The recess 98 is offset from the rotational axis 46 ofthe crank arm 78 so that the axis of the recess 98 is aligned with theaxis 54 and is eccentrically positioned relative to the actuator axis46.

The bearing assembly 56 is positioned within the recess 98. The bearingassembly 56 includes a handle bearing portion 100 which is preferably abushing type journal bearing operable to carry both radial and thrustloads. The handle bearing 100 is retained within the recess 98 and, inturn, receives a cup-shaped bellows cap 102. The handle bearing 100supports the bellows cap 102 for rotation relative to the crank arm 78.The bellows cap 102, in turn, receives a stem bearing 104 which ispreferably a bushing-type journal bearing operable to carry radialloads. The stem bearing 104 is positioned in surrounding relation withthe valve stem upper end portion 52 and permits the bellows cap 102 torotate relative to the valve stem upper end portion 52. The stem bearing104 is positioned on a stem shoulder 103 to position the bearing 104 onthe stem upper end portion 52 for axial movement of the bellows cap 102in response to upward axial forces exerted on the valve stem 36.

The bellows cap 102 is closed at one end portion to surround and sealthe valve stem upper end portion 52 within the recessed end portion 94of the crank arm 78. The bellows cap 102 includes a flanged open endportion positioned opposite the bellows upper end portion 66. Thebellows upper end portion 66 is welded at 106 to the flanged end of thebellows cap 102. This arrangement permits relative rotation between thecrank arm 78 and the bellows cap 102 welded to the bellows upper endportion 66. Further, relative rotation is permitted between the bellowscap 102 and the valve stem upper end portion 52. By the combination ofthe thrust and radial bearings 100 and 104 torque is transmitted fromthe crank arm 78 to the valve stem 36 as the valve stem upper endportion 52 orbits or turns about the stationary rotational vertical axis46 of the crank arm 78.

The welded connection of the bellows upper end portion 66 to the flangedend of the bellows cap 102 around the valve stem upper end portion 52hermetically seals the valve stem upper end portion 52 within thehousing 80. The welded connection provided at 106 between the bellows 58and the bellows cap 102 forms a valve primary pressure boundary toprevent the escape of line fluid and pressure around the valve stem 36.A secondary pressure boundary is formed by the O-ring 88 sealinglypositioned between the housing 80 and crank arm 78. Thus, the crank arm78 and housing 80 not only function as a means for actuating the valve10 but also are operable in combination with O-ring 88 as a dynamic sealto back up the primary pressure boundary provided by the bent bellows58.

The housing 80 is operable in the event of bellows failure or any leakacross the primary pressure boundary to contain the fluid and full linepressure within the chamber 84. This arrangement permits high pressuresand hazardous or contaminated fluids to be contained within the valveassembly 10 and prevents their escape to the environment in the event ofa primary pressure boundary failure. One advantage of the paralleloffset between the axes 46 and 54 is a reduced clearance around axis 46for the crank arm 78. This permits the inside diameter of the housing 80and, therefore, the size of the chamber 84 to be substantially reducedwhile at the same time serve as a back-up pressure boundary. Reducingthe inside diameter of housing 80 permits the wall thickness of housing80 to be reduced without a decrease in the capability of the housing 80to withstand internal pressure. This provides lighter, and lessexpensive secondary pressure boundary than otherwise permitted.

The housing 80 maintains the rotational axis of the crank arm 78 alignedwith the axis 46 which is, in turn, aligned with the axis 50. Rotationof the crank arm 78 about the rotational axis 46 is maintained by theposition of a flanged lower end portion 108 of the housing 80 within arecess 110 of the valve central body portion 20. The flanged end portion108 is guided into position on the valve central body portion 20 byengagement with the recess 110. Surfaces 112 of the housing end portion108 abut the wall of recess 110. In this manner, the housing 80 isprecisely located on the central body portion 20 so that the axis ofrotation of the crank arm 78 is maintained in alignment with the axes 46and 50. The bellows plate 68 is similarly aligned with axes 46 and 50 bya radially abutting relationship with bearing 70. The bearing 70 isaligned by a radially abutting relationship with bore 71 which iscoaxially aligned with axes 46 and 50.

To operate the valve assembly 10 and move the valve member 34 betweenthe open and closed positions within the valve chamber 26, torque isapplied to the handle 90 to rotate the crank arm 78 about the axis 46to, in turn, orbit the enlarged lower end portion 94 and the valve stemupper end portion 52 about the axis 46. This initiates turning of thevalve stem lower end portion 48 about the axis 50 and rotation of thevalve member 34 about the axis 50. The bellows cap 102 also orbits withthe valve stem upper end portion 52 about the axis 46. Rotation of thecrank arm 78 is transmitted through the handle bearing 100, the bellowscap 102, and the stem bearing 104 to the stem upper end portion 52.Thus, rotation is transmitted by a force eccentrically applied to thestem upper end portion 52. The valve actuating force is transmitted bytorque applied outside the primary and secondary pressure boundariesthrough the bent bellows 58 to the valve member 34.

While the bellows cap 102 orbits around axis 46, it does not rotateabout axis 54. The primary pressure boundary elements including thebellows 58 and bellows cap 102 are fixed from rotating relative to axes46 and 50; however, the bellows 58 flexes permitting the bellows cap 102to orbit in an arc around the axis 46. The end portion 94 and valve stemupper end portion rotate about axes 46 and 50. The bearings 100 and 104support the bellows cap 102 for rotation relative to the end portion 94and the stem upper end portion 52.

Further in accordance with the present invention, the thrust bearing 96,handle bearing 100, and the stem bearing 104 are provided withsufficient length and structural strength to prevent binding of therotational connection of the valve stem upper end portion 52 to theactuator 38. Thus, the various connecting parts therebetween are notlaterally displaced from the offset and parallel alignment as abovedescribed. This maintains the actuator axis 46 in spaced parallelrelation to the valve stem upper end portion axis 54.

In operation of the valve assembly 10 with the pressure in cavity 22greater than the pressure externally of housing 80, the bellows 58 isinternally pressurized and consequently upward thrust forces are exertedwithin the bellows upon the bearing assembly 56. However, it should beunderstood that the present invention is also operable in low pressureand vacuum conditions. The combination of the bearings 96, 100 and 104resist the radial and thrust forces applied from the pressure within thebellows 58 to maintain relative rotation between the crank arm 78 andthe valve stem upper end portion 52. This arrangement of maintaining theaxes 46 and 54 parallel also permits axial movement of the valve stemupper end portion 52 during operation of the valve 10. Also thisarrangement does not exert a biasing force on the bellows 58, thus thereis no "springback" effect on the bellows 58.

By maintaining the rotational axes 46 and 54 in spaced parallelrelation, a relatively conventional rotatable actuator, such as thehandle 90 connected to the crank arm 78, is utilized with the presentinvention. The torque applied to the handle 90 is transmitted by thecrank arm 78 to the offset crank arm end portion 94 thereby transmittinga force to the valve stem upper end portion 52 which is offset from therotational force transmitted to the crank arm 78. In addition, byproviding both the valve stem 36 and the bellows 58 with a double orreverse curvature, as illustrated in FIG. 1, the parts connecting thevalve stem upper end portion 52 to the actuator 38 are free of inclinedor angled surfaces. By maintaining these connections at either rightangles or in spaced parallel relation, axial movement between the valvestem 36 and the valve actuator 38 is taken up by the bearing assembly56. The bearing assembly 56 maintains any displacement that occurs in anaxial direction. This eliminates any lateral forces acting on the valvestem upper end portion 52 which would otherwise tend to bind or cock theconnection of the valve stem upper end portion 52 to the crank arm 78during rotation. In addition, fabrication of these surfaces is lesscostly because only conventional parallel and perpendicular surfaces arerequired.

In operation, the bellows 58 is internally pressurized by the pressureinside cavity 22. As a result, an accordion, expansion effect takesplace on the bellows and the bellows 58 is urged to expand axially.However, with the end portions of the bellows 58 axially fixed, theaxial forces acting on the bellows 58 are transmitted from the bellowsupper end portion 66 to the bellows cap 102. The bellows cap 102 isurged upwardly in a direction parallel to the axis 46. This upward axialforce applied to the bellows cap 102 is taken up by the combination ofradial and thrust bearings, 96, 100 and 104 which provide for limitedaxial displacement of the connected parts. Thus, by maintaining therotational axes 46 and 54 in spaced parallel relation, any axial forcesapplied to the valve stem 36 and bellows 58 are taken up by the bearingassembly 56. The pressure forces are maintained in an axial direction.The valve stem upper end portion 52 remains rotatable relative to thecrank arm 78. Forces acting in a radial direction are restrained toprevent binding of the relatively rotating parts.

Internally pressurizing the bellows 58 exerts upward and lateral forcesupon the bellows, generating rubbing or frictional engagement of theinner surface of the bellows 58 with the outer surface of the valve stem36. In view of the fact that the valve stem 36 rotates within thebellows 58 and contacts the inner surface of the bellows 58, the bellows58 conforms to the configuration of the valve stem 36. The bellows tendsto be naturally unstable and, therefore, subject to distortion. Theinstability of the bellows 58 is further compounded by the fact that thebellows is internally pressurized. The total effect of bending thebellows and internally pressurizing the bellows is to increase thefrictional contact of the bellows with the valve stem. Wear of thebellows can result thereby reducing the cycle life of the bellows andthe capability of the bellows to maintain a primary pressure boundaryaround the valve stem 36.

As pressure is applied to the inside of the bellows 58, the bellows willtend to deflect laterally or "squirm". A deficiency with any bellows,especially an elongated, flexible bellows, is the limited maximuminternal pressure which the bellows can sustain. This is not based onthe bellows wall strength or rupture pressure but upon the "squirm"pressure which is lower than the bellows rupture pressure. The "squirm"pressure is the pressure at which a straight, unsupported bellowsdeflects when internally pressurized. This action is comparable to along slender rod buckling under a compressive load.

To enhance the stability of the initially flexed bellows 58, a reducedclearance is provided between the valve stem 36 and the bellows 58 tothe extent that the bellows 58 is supported substantially along itsflexed length by the valve stem 36. In this manner, the valve stem 36restrains uncontrolled buckling or "squirm" of the bellows 58.Preferably the clearance between the outer surface of the valve stem 36and the inner surface of the bellows 58 distributes the surface contactbetween the bellows and the valve stem over substantially the entirelength of the bellows.

By providing a maximized gradual curvature to the valve stem 36, asillustrated in FIG. 7 and thus to the bellows 58, the amount of flexingof each bellows convolute is minimized. In the bent portion of thebellows 58, each convolute is tilted or flexed toward either axis 46 oraxis 54. As the bellows orbits around axis 54, each convolute maintainsthe same magnitude of flex but the orientation of flexing rotates tocorrespond to the rotation of axis 54. The cyclic flexing of eachconvolute generates fatigue leading to bellows failure. The internalpressure will additionally influence the flexing cycle life. With thearrangement shown in FIG. 7, however, the stem 36 and bellows 58 areformed with a uniform curvature having a radius R in each bent portion,as diagrammatically illustrated in FIG. 7. Each bent portion has thesame radius of curvature, R. Preferably, the two bent portions areuninterrupted so that the reverse curvature has no intermediate straightsection. With this arrangement, the maximum radius of bellows curvatureis used to obtain a preselected offset of axes 50 and 54. Thus, bymaximizing the radius R of bellows curvature, the flex of each bellowsconvolute is minimized to increase the cycle life of the bellows 58. Thebellows can withstand higher pressures and increased torque can beapplied to the valve actuator 38 in the valve assembly 10 having acompact configuration.

By increasing the area of contact between the valve stem 36 and thebellows 58, the overall stability of the bellows 58 is increased andlocalized distortion or buckling of the bellows at concentrated pointsis eliminated. With the present invention a substantial number of theconvolutions of the bellows 58 are in contact with the valve stem 36,thereby minimizing buckling of the bellows 58 when pressurized. Becauseof the relative rotary rubbing motion of the bellows and stem, it isdesirable to minimize the wear and friction between these two parts.Wear of the bellows is undesirable primarily because the bellows isrelatively thin and only a minor amount of wear will diminish thebellows wall thickness to a point resulting in bellows failure. Bellowswear is also accelerated by the friction generated between the stem andbellows when torque is applied to the stem.

To prevent wear of the bellows 58 by contact with the valve stem 36, thestem 36 is provided with a low friction outer surface or stem coating.FIGS. 8-10 illustrate various embodiments of the bent valve stem havinga low friction outer surface adaptable for supporting a bellows with aminimum of wear in accordance with the present invention.

As the valve assembly 10 is operated to rotate the valve member 34 thebellows 58 flexes around the valve stem 36 as the stem rotates withinthe bellows 58. The bellows 58 does not rotate but the stem 36 rotatesrelative to the bellows 58. Both the valve stem upper end portion 52 andthe bellows upper end portion 66 orbit about the axis 46. The valve stemupper end portion 52 rotates relative to the valve central body portion20 during said orbital movement, but the bellows upper end portion 66does not rotate during the orbital movement. Subsequently a rubbingmotion is generated between the valve stem 36 and the bellows 58.

The friction generated between the valve stem 36 and the bellows 58 canalso be reduced by the application of a wear resistant stem coating orstem plating. For example, as illustrated in FIG. 8, a wear resistantmaterial, such as a plastic material in the form of a sleeve 118 ismolded in surrounding relation with the embodiment of a valve stem 120having a reduced outer diameter and enlarged shoulder end portions 122and 124 for receiving the sleeve 118. Preferably the sleeve 118 ismolded or bonded to the outer surface of the valve stem 120. Mostpreferably the sleeve 118 is fabricated of a material which isdeformable or resilient in order to reduce the friction between thebellows and the sleeve 118.

A further embodiment of a wear resistant surface around the valve stemis illustrated in FIG. 9 in which a valve stem 126 is surrounded by aplurality of resilient rings 128 fabricated of a suitable deformablematerial, such as plastic. In one embodiment the rings 128 are split andin another embodiment the rings 128 are unitary. The rings 128 arearranged in a stacked relation on the stem 126. The bellows (not shown)engages the rings 128 which serve to reduce the friction generatedbetween stem 126 and the bellows.

FIG. 10 illustrates another embodiment of a valve stem 130 having a wearresistant plating 132 deposited thereon for supporting the bellows witha minimum of wear of the valve stem 130. In this manner, the plating 132provides a build-up of metal on the valve stem 130 which conforms to thebent configuration of the valve stem. Further, the plating 132 may befabricated of a material that is softer than the material of the bellowsso that the plate 132 wears and not the bellows around the plate 132.The plating 132 in another embodiment is a material harder than thematerial of the bellows so that frictional forces and wear of thebellows 58 and plating 132 is reduced.

Another approach to preventing wear of the bellows by frictionalengagement with the valve stem is to plate the inner surface of thebellows. FIG. 6 illustrates a bellows 134 positioned in surroundingrelation with a valve stem 136. The bellows 134 includes an innersurface which is built up by the addition of plating 138 formed integralwith the bellows 134. The plating 138 may be fabricated of either amaterial softer than the material of the valve stem 136 or harder thanthe material of the valve stem 136.

As is well known, a bellows is formed of a plurality of convolutions140. Because of the nature of plating irregular surfaces, specificallythe inner surface of the bellows convolutions 140, an increased materialthickness is formed on tte sharply curved inner surfaces where wear ofthe convolutions 140 is the most severe. Thus, by plating the innersurface of the bellows, a maximum plating thickness is provided wherethe wear is the greatest, i.e. at the convolutions where the bellowsrubs against the valve stem.

In accordance with the present invention, the convoluted structure ofthe bellows may be designed to reduce the wear of the bellows due tofrictional engagement with the valve stem. Referring to FIG. 5, there isillustrated a valve stem 142 surrounded by a bellows generallydesignated by the numeral 144. The bellows 144 is fabricated by apreselected material such as metal, and includes a plurality ofconvolutions 146 having a preselected radii. Each convolution 146includes horizontally extending surfaces 148 formed integral withvertically extending sections 150 to thereby connect adjacentconvolutions. The vertically extending sections or flats 150 between theconvolutions 146 have an inner surface positioned opposite the outersurface of the valve stem.

A suitable wear resistant material 152 as illustrated in FIG. 5 may bebonded or secured to the inner surfaces of the vertically extendingsections 150. In this manner, the arcuately shaped convolutions 146 aremoved from contact with the valve stem and the sections 150 that extendin an axial direction parallel to the axis of the valve stem are theonly sections of the bellows 134 engageable with the valve stem. Theparallel alignment of the sections 150 with the axis of the valve stem142 minimizes wear of the bellows by distributing frictional engagementof the valve stem 142 with the bellows 144 over a greater surface areaof the bellows, i.e. over the wear resistant sections 150.

FIG. 7 illustrates bearing support of the valve stem 36 by a pluralityof ball bearings generally designated by the numerals 114 and 116positioned in surrounding relation with the valve stem end portions 48and 52. The bellows (not shown in FIG. 7) is positioned in surroundingrelation on the stem 36. The ball bearings 114 and 116 can be used inlieu of bearings 70 and 104 illustrated in FIG. 1. In a similar manner,thrust or radial ball bearings can be used in lieu of bearings 96 and100 in FIG. 1. The ball bearings 114 an 116 function as rotational wearresistant devices operable to reduce friction. As further illustrated inFIG. 7, the valve stem upper end portion 52 does not require a stemshoulder to maintain the ball bearings 114 in place.

Now referring to FIGS. 2 and 3, there is illustrated a first embodimentof apparatus for limiting rotation of the valve actuator 30 to move thevalve member 34 between the open and closed positions in the valvechamber 26. FIGS. 2 and 3 schematically illustrate the crank arm 78 withthe details of the connection of the valve stem 36 and the bellows 58 tothe crank arm 78 omitted to more clearly illustrate a valve stopmechanism generally designated by the numeral 154. Only the lowerportion 142 of the valve stem is shown in FIG. 3. In the embodimentshown in FIGS. 2 and 3 the valve stop mechanism 154 is operable to limitrotation of the actuator 38 and the valve stem 36 to 90° rotationbetween the open and closed positions.

As described above, the crank arm 78 includes the enlarged end portion94 which is eccentrically positioned relative to the rotational axis 46of the crank arm 78. Thus, the enlarged end portion 94 has a peripheralsurface positioned closely adjacent to the inner surface of the stemhousing 80. The stop mechanism 154 includes a pair of protuberances 156that are secured to and extend inwardly from the wall of the housing 80.The protuberances 156 are positioned at an elevation on the housing 80so that they project inwardly and oppositely of the periphery of theenlarged end portion 94. When the handle 90 is turned, the enlarged endportion 94 contacts the protuberances 156 obstructing further rotationof the crank arm 78 and the valve stem 36.

Preferably, the protuberances 156 are spaced on the housing 80 to permitunobstructed rotation of the crank arm 78 through a 90° angle. When thehandle is rotated to the extent that the enlarged end portion 94 ismoved into abutting relation with the protuberance 158 the valveassembly 10 is in the open position. Accordingly, rotation of the handle90 in the opposite direction moves the enlarged end portion 94 out ofcontact with the protuberance 156 and toward and eventually into contactwith the protuberance 156. Rotation of the handle 90 in this directionmoves the valve member 34 from the open position illustrated in FIG. 1to a closed position where the valve member 34 blocks flow through thevalve chamber 26.

In order to insure that the through bore 44 of the valve body 40 isaligned with the passageways 28 and 30 to open the valve 10, theprotuberance 156 must be located at the selected point on the interiorwall of the housing 80 where contact of the protuberance with theenlarged end portion 94 corresponds to the position where the bore 44 isaligned with the passageways 28 and 30. Also, the protuberance 158 mustbe positioned at the point on the interior wall of the housing 80 wherewhen contacted by the enlarged end portion 94, the solid faces of thevalve member 34 have been moved into a position within the chamber 26obstructing flow between the passageways 28 and 30. In this manner, thevalve member 34 is limited to rotation through 90° where the end pointsof rotation of the valve member 34 correspond to the open and closedpositions of the valve.

Now referring to FIG. 4, there is illustrated another embodiment of avalve stop mechanism generally designated by the numeral 160 forlimiting rotation of the valve stem 36 to, in turn, control rotation ofthe valve member 34 and assure that the valve member is positively movedbetween the open and closed positions. The valve stop mechanism 160illustrated in FIG. 4 includes an annular recess 162 formed in thebellows plate 68 in surrounding relation with the valve stem lower endportion 142. The bellows plate 68 is sealingly engaged to the valvecentral body portion 20 by the circumferential weld 74 that extendscompletely around the periphery of the bellows plate 68 or any othersuitable static seals. To limit the valve stem 36 to 90° rotation, apair of stop pins 164 (only one of which is illustrated in FIG. 4)extends upwardly from the valve central body portion 20 into the annularrecess 162. Secured to and extending outwardly from the valve stem lowerend portion 142 is a pin 166. The pin 166 has a length which permits thepin 166 to extend outwardly from the lower end portion 142 stem adistance greater than the spacing of the stop pin 164 from the stem 36.

The stop pins 164 are precisely located on the central body portion 20within the annular recess 162 so that when the pin 166 is in contactwith either stop pin 164 the valve member 34 is either in the open orclosed position. The pin 166 engaging the pin 164, as shown in FIG. 4corresponds to the open position of the valve. Depending on the designclearances between the several actuator parts, significant "play" mayexist between the handle 90 and the valve member 34. This results ingreater than 90° rotation of the handle 90, such as 100° rotation, tomove the valve member 34 between the open and closed positions. However,the handle 90 is turned until rotation is obstructed by contact with theroll pin 166 with either one of the stop pins 164. Thus, the handle 90is not limited to precisely 90° rotation and "play" may occur in thehandle as the valve member 34 is positively rotated through 90° into andout of the open and closed positions of the valve. The operator may findthat between the open and closed positions of the valve, the handle 90rotates through an angle greater than 90°. However, the end limits ofrotation of the valve stem 36 precisely locate the valve member 34 ineither the open or closed position.

Now referring to FIG. 11, there is schematically illustrated anotherembodiment of the stem housing 80 which surrounds the bellows 58 and thevalve stem 36. As illustrated in FIGS. 1, 3 and 4, the housing 80 formsthe chamber 84 around the bellows 58. The chamber 84 serves as asecondary pressure boundary to back up the primary pressure boundaryprovided by the bellows 58 around the valve stem 36. In operation, thechamber 84 is not pressurized unless the primary pressure boundaryprovided by the bellows 58 fails. Therefore, a bellows failure indicatorgenerally designated by the numeral 168 in FIG. 11 is provided on thehousing 80 to sense a pressure buildup within the chamber 84. A buildupof pressure within the chamber 84 indicates failure of the bellows 58 toprevent fluid leakage around the valve stem 36. The bellows failureindicator 168 preferably includes a pressure guage, a pressure switch,or any other device operable to indicate that the bellows 58 has failedand fluid is leaking between the bellows 58 and the valve stem 36. Theindicator 168 is suitably connected to the housing 80. An opening 170through the housing permits the indicator 168 to be exposed to thepressure conditions within the chamber 84.

According to the provisions of the patent statutes, we have explainedthe principle, preferred construction and mode of operation of ourinvention and have illustrated and described what we now consider torepresent its best embodiments. However, it should be understood that,within the scope of the appended claims, the invention may be practicedotherwise than as specifically illustrated and described.

We claim:
 1. A valve comprising,a valve body, a passageway extendingthrough said valve body for the flow of fluid therethrough, a valvemember positioned in said passageway for movement between an openposition and a closed position to open and close said passageway,actuating means rotatable about an axis for moving said valve memberbetween the open position and the closed position, a valve stemextending between said valve member and said actuating means, said valvestem having an upper end portion, bearing means carried by saidactuating means for connecting said actuating means to said valve stemupper end portion to transmit rotation from said actuating means to saidvalve stem, said valve stem having a lower end portion connected to saidvalve member for transmission of rotation from said actuating means tosaid valve member, said bearing means being positioned on said actuatingmeans laterally displaced from said actuating means axis, said valvestem upper end portion having an axis of rotation and said valve stemlower end portion having an axis of rotation, said valve stem lower endportion axis being axially aligned with said actuating means axis, saidvalve stem upper end portion axis being laterally displaced from saidactuating means axis and said valve stem lower end portion axis toprovide said valve stem with a bent configuration, said valve stem upperend portion being rotatably received in said bearing means to maintainsaid valve stem upper end portion axis in spaced relation to saidactuating means axis, a bellows surrounding said valve stem to provide ahermetic seal around said valve stem between said valve body and saidactuating means, said bellows having a bent configuration correspondingto the bent configuration of said valve stem, said valve stem having anouter surface and said bellows having an inner surface positionedclosely adjacent to said valve stem outer surface such that said valvestem supports said bellows against lateral deflection when subjected topressure forces to prevent distortion of said bellows, and wearresistant means positioned between said valve stem outer surface andsaid bellows inner surface for reducing the frictional wear between saidbellows and said valve stem.
 2. A valve as set forth in claim 1 inwhich,said bellows being positioned in close proximity to said valvestem to flex in conformity with said bend in said valve stem, and saidwear resistant means includes a solid lubricant coating maintained incontact with said bellows inner surface substantially along the entireflexed length thereof by said valve stem outer surface.
 3. A valve asset for in claim 1 in which,said wear resistant means includes platingpositioned on said bellows inner surface to reduce wear of said innersurface upon contact with said valve stem outer surface.
 4. A valve asset forth in claim 1 in which,said wear resistant means is positioned onsaid valve stem outer surface and in contact with said bellows innersurface for reducing the frictional contact between said valve stem andsaid bellows to prevent wear of said bellows.
 5. A valve as set forth inclaim 1 in which,said actuating means includes a lower end portionoffset from said actuating means axis, a recess in said actuating meanslower end portion, said recess having an axis coaxial with said valvestem upper end portion axis, said bearing means positioned in saidrecess and surrounding said valve stem fro supporting said actuatingmeans on said valve stem to only permit movement of said actuating meansrelative to said valve stem in a direction along said valve stem upperend portion axis without generating abrasion of said stem, and saidbearing means restraining said valve stem upper end portion from movinglaterally to prevent binding of said actuating means with said valvestem.
 6. A valve as set forth in claim 1 in which,said bellows includesa lower end portion, a bellows plate positioned on said valve body insurrounding relation with said valve stem, a first circumferential weldsurrounding said bellows plate for sealingly connecting said bellowsplate to said valve body, and a second circumferential weld surroundingsaid bellows lower end portion for connecting said bellows to saidbellows plate to provide a hermetic seal around said valve stem at saidbellows lower end portion.
 7. A valve as set forth in claim 1 whichincludes,a housing surrounding said bellows and extending between saidactuating means and said valve body to form a back-up pressure boundaryaround said valve stem in addition to the hermetic seal provided by saidbellows around said valve stem, a sealed chamber formed between saidhousing and said bellows, indicator means associated with said housingfor sensing a failure of the hermetic seal and pressure leakage throughsaid bellows around said valve stem, and said housing being operable tocontain the pressure leakage within said chamber.
 8. A valve,comprisinga valve body, a passageway extending through said valve bodyfor the flow of fluid therethrough, a valve member positioned in saidpassageway for movement between an open position and a closed positionto open and close said passageway, actuating means rotatable about anaxis for moving said valve member between the open position and theclosed position, a valve stem extending between said valve member andsaid actuating means, said valve stem having a lower end portionconnected to said valve member and an upper end portion connected tosaid actuating means for transmission of rotation from said actuatingmeans to said valve member, said valve stem upper end portion beingdisplaced from said valve stem lower end portion to provide said valvestem with a bent configuration, a bellows surrounding said valve stem toprovide a hermetic seal around said valve stem between said valve bodyand said actuating means, said bellows having a bent configurationcorresponding to the bent configuration of said valve stem, said valvestem having an outer surface and said bellows having an inner surfacepositioned closely adjacent to said valve stem outer surface such thatsaid valve stem supports said bellows against lateral deflection whensubjected to pressure forces to prevent distortion of said bellows, andcoating means positioned on said valve stem outer surface for reducingthe frictional contact between said valve stem and said bellows toprevent wear of said bellows.
 9. A valve as set forth in claim 8 inwhich,said coating means includes a sleeve member surrounding said valvestem outer surface and secured thereto, and said sleeve supporting saidbellows on said valve stem to reduce abrasion of said bellows innersurface upon contact with said sleeve.
 10. A valve as set forth in claim8 which,said coating means includes a resilient wear resistant materialmolded onto said valve stem outer surface, and said resilient wearresistant material supporting said bellows on said valve stem to reduceabrasion of said bellows inner surface upon contact with said sleeve.11. A valve comprising,a valve body, a passageway extending through saidvalve body for the flow therethrough, a valve member positioned in saidpassageway for movement between an open position and a closed positionto open and close said passageway, actuating means rotatable about anaxis for moving said valve member between the open position and theclosed position, a valve stem extending between said valve member andsaid actuating means, said valve stem having a lower end portionconnected to said valve member and an upper end portion connected tosaid actuating means for transmission of rotation from said actuatingmeans to said valve member, said valve stem upper end portion beingdisplaced from said valve stem lower end portion to provide said valvestem with a bent configuration, a bellows surrounding said valve stem toprovide a hermetic seal around said valve stem between said valve bodyand said actuating means, said bellows having a bent configurationcorresponding to the bent configuration of said valve stem, said valvestem having an outer surface and said bellows having an inner surface,and a plurality of ring members positioned on said valve stem to supportsaid bellows and remove said bellows inner surface from contact withsaid valve stem outer surface to reduce frictional wear between saidbellows and said valve stem.
 12. A valve comprising,a valve body, apassageway extending through said valve body for the flow of fluidtherethrough, a valve member positioned in said passageway for movementbetween an open position and a closed position to open and close saidpassageway, actuating means rotatable about an axis for moving saidvalve member between the open position and the closed position, a valvestem extending between said valve member and said actuating means, saidvalve stem having a lower end portion connected to said valve member andan upper end portion connected to said actuating means for transmissionof rotation from said actuating means to said valve member, said valvestem upper end portion being displaced from said valve stem lower endportion to provide said valve stem with a bent configuration, a bellowssurrounding said valve stem to provide a hermetic seal around said valvestem between said valve body and said actuating means, said bellowshaving a bent configuration corresponding to the bent configuration ofsaid valve stem, said valve stem having an outer surface and saidbellows having an inner surface positioned closely adjacent to saidvalve stem outer surface such that said valve stem supports said bellowsagainst lateral deflection when subjected to pressure forces to preventdistortion of said bellows, said bellows inner surface includes aplurality of flats connected by a plurality of convolutes, said flatsbeing positioned in substantially spaced parallel relation with saidvalve stem outer surface and said convolutes being removed form contactwith said valve stem outer surface, a wear resistant material secured tosaid flats and positioned between said flats and said valve stem outersurface, and said flats with said wear resistant material being arrangedto minimize wear of said bellows by uniformly distributing thefrictional engagement of said valve stem with said bellows over thesurfaces of said flats substantially along the entire length of saidbellows.